Theaspiran[2,6,10,10-tetramethyl-1-oxa-spiro[4,5]-deca-6-en] is a compound known as a flavor component which is contained in a minute amount in various essential oils such as raspberry oil and passion fruit oil (Non-patent Literature 1), especially it has been known to be useful as a aromatic flavor component (Patent Literature 1). However, theaspiran has asymmetric carbons at the second position and fifth position, giving 4 stereoisomers, and the mixture ratio of the isomers has been known to vary depending on a source of the essential oils (Non-patent Literature 2 and Non-patent Literature 3). In the circumstances, various processes for the production of theaspiran have been studied (Patent Literature 2, Patent Literature 3, etc.); however, their products are racemates, while a synthesis of an optically active compound reported in Non-patent Literature 2 comprises esterification by chiral phenyl propionic acid and HPLC separation, thereby the synthesis was usable for microsynthesis but not for practical use. Therefore, an inexpensive method for industrial production of theaspiran as a flavor component has been desired.    Non-patent Literature 1: Helv. Chim. Acta 57, 1301 (1974)    Non-patent Literature 2: J. Agric. Food Chem., 40, 1188 (1992)    Non-patent Literature 3: Z. Lebensm. Unters. Forsch., 196, 307 (1993)    Patent Literature 1: JP-A-60-1119    Patent Literature 2: JP-A-53-92757    Patent Literature 3: JP-A-61-134386